Optical elements that provide acceptable imaging qualities while maintaining durability and abrasion resistance are sought for a variety of applications, such as windshields, sunglasses, fashion lenses, non-prescription and prescription lenses, sport masks, face shields and goggles. Responsive to that need, coated optical elements have been developed.
However, often the coatings lack sufficient adhesion to a substrate to provide long wear. Coatings such as photochromic coatings and protective tie-layer coatings have been developed containing adhesion promoters such as epoxides and aminoalkyltrialkoxysilanes to enhance adhesion of coatings to the substrate and/or to subsequently applied coatings. However, such adhesion promoters have highly reactive functional groups that may lead to instability and reduced shelf life of coating compositions. Blocked isocyanates have also been used, but when the deblocking temperature of the blocking agent exceeds the curing temperature of the resinous components, the adhesion promoters may not be as effective as necessary.
There is a need in the art to develop optical articles containing coating compositions with adhesion promoters that will be effective at improving adhesion at or below curing temperatures, yet will not interfere with composition shelf life.